[mirror_ubuntu-artful-kernel.git] / net / dccp / input.c

/*
 *  net/dccp/input.c
 * 
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/dccp.h>
#include <linux/skbuff.h>

#include <net/sock.h>

#include "ccid.h"
#include "dccp.h"

static void dccp_fin(struct sock *sk, struct sk_buff *skb)
{
	sk->sk_shutdown |= RCV_SHUTDOWN;
	sock_set_flag(sk, SOCK_DONE);
	__skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
	__skb_queue_tail(&sk->sk_receive_queue, skb);
	skb_set_owner_r(skb, sk);
	sk->sk_data_ready(sk, 0);
}

static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
{
	switch (sk->sk_state) {
	case DCCP_PARTOPEN:
	case DCCP_OPEN:
		dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
		dccp_fin(sk, skb);
		dccp_set_state(sk, DCCP_CLOSED);
		break;
	}
}

static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
{
	/*
	 *   Step 7: Check for unexpected packet types
	 *      If (S.is_server and P.type == CloseReq)
	 *	  Send Sync packet acknowledging P.seqno
	 *	  Drop packet and return
	 */
	if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		return;
	}

	switch (sk->sk_state) {
	case DCCP_PARTOPEN:
	case DCCP_OPEN:
		dccp_set_state(sk, DCCP_CLOSING);
		dccp_send_close(sk);
		break;
	}
}

static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
{
	struct dccp_sock *dp = dccp_sk(sk);

	if (dp->dccps_options.dccpo_send_ack_vector)
		dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
					     DCCP_SKB_CB(skb)->dccpd_ack_seq);
}

static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
{
	const struct dccp_hdr *dh = dccp_hdr(skb);
	struct dccp_sock *dp = dccp_sk(sk);
	u64 lswl = dp->dccps_swl;
	u64 lawl = dp->dccps_awl;

	/*
	 *   Step 5: Prepare sequence numbers for Sync
	 *     If P.type == Sync or P.type == SyncAck,
	 *	  If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
	 *	     / * P is valid, so update sequence number variables
	 *		 accordingly.  After this update, P will pass the tests
	 *		 in Step 6.  A SyncAck is generated if necessary in
	 *		 Step 15 * /
	 *	     Update S.GSR, S.SWL, S.SWH
	 *	  Otherwise,
	 *	     Drop packet and return
	 */
	if (dh->dccph_type == DCCP_PKT_SYNC || 
	    dh->dccph_type == DCCP_PKT_SYNCACK) {
		if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
			      dp->dccps_awl, dp->dccps_awh) &&
		    !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
			dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		else
			return -1;
	/*
	 *   Step 6: Check sequence numbers
	 *      Let LSWL = S.SWL and LAWL = S.AWL
	 *      If P.type == CloseReq or P.type == Close or P.type == Reset,
	 *	  LSWL := S.GSR + 1, LAWL := S.GAR
	 *      If LSWL <= P.seqno <= S.SWH
	 *	     and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
	 *	  Update S.GSR, S.SWL, S.SWH
	 *	  If P.type != Sync,
	 *	     Update S.GAR
	 *      Otherwise,
	 *	  Send Sync packet acknowledging P.seqno
	 *	  Drop packet and return
	 */
	} else if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
		   dh->dccph_type == DCCP_PKT_CLOSE ||
		   dh->dccph_type == DCCP_PKT_RESET) {
		lswl = dp->dccps_gsr;
		dccp_inc_seqno(&lswl);
		lawl = dp->dccps_gar;
	}

	if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
	    (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
	     between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
		       lawl, dp->dccps_awh))) {
		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);

		if (dh->dccph_type != DCCP_PKT_SYNC &&
		    (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
		     DCCP_PKT_WITHOUT_ACK_SEQ))
			dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
	} else {
		dccp_pr_debug("Step 6 failed, sending SYNC...\n");
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		return -1;
	}

	return 0;
}

int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
			 const struct dccp_hdr *dh, const unsigned len)
{
	struct dccp_sock *dp = dccp_sk(sk);

	if (dccp_check_seqno(sk, skb))
		goto discard;

	if (dccp_parse_options(sk, skb))
		goto discard;

	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
		dccp_event_ack_recv(sk, skb);

	/*
	 * FIXME: check ECN to see if we should use
	 * DCCP_ACKPKTS_STATE_ECN_MARKED
	 */
	if (dp->dccps_options.dccpo_send_ack_vector) {
		struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;

		if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
				     DCCP_SKB_CB(skb)->dccpd_seq,
				     DCCP_ACKPKTS_STATE_RECEIVED)) {
			LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable "
						 "packets buffer full!\n");
			ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
			inet_csk_schedule_ack(sk);
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
						  TCP_DELACK_MIN,
						  DCCP_RTO_MAX);
			goto discard;
		}

		/*
		 * FIXME: this activation is probably wrong, have to study more
		 * TCP delack machinery and how it fits into DCCP draft, but
		 * for now it kinda "works" 8)
		 */
		if (!inet_csk_ack_scheduled(sk)) {
			inet_csk_schedule_ack(sk);
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
						  DCCP_RTO_MAX);
		}
	}

	ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
	ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);

	switch (dccp_hdr(skb)->dccph_type) {
	case DCCP_PKT_DATAACK:
	case DCCP_PKT_DATA:
		/*
		 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
		 * option if it is.
		 */
		__skb_pull(skb, dh->dccph_doff * 4);
		__skb_queue_tail(&sk->sk_receive_queue, skb);
		skb_set_owner_r(skb, sk);
		sk->sk_data_ready(sk, 0);
		return 0;
	case DCCP_PKT_ACK:
		goto discard;
	case DCCP_PKT_RESET:
		/*
		 *  Step 9: Process Reset
		 *	If P.type == Reset,
		 *		Tear down connection
		 *		S.state := TIMEWAIT
		 *		Set TIMEWAIT timer
		 *		Drop packet and return
		*/
		dccp_fin(sk, skb);
		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
		return 0;
	case DCCP_PKT_CLOSEREQ:
		dccp_rcv_closereq(sk, skb);
		goto discard;
	case DCCP_PKT_CLOSE:
		dccp_rcv_close(sk, skb);
		return 0;
	case DCCP_PKT_REQUEST:
		/* Step 7 
            	 *   or (S.is_server and P.type == Response)
		 *   or (S.is_client and P.type == Request)
		 *   or (S.state >= OPEN and P.type == Request
		 *	and P.seqno >= S.OSR)
		 *    or (S.state >= OPEN and P.type == Response
		 *	and P.seqno >= S.OSR)
		 *    or (S.state == RESPOND and P.type == Data),
		 *  Send Sync packet acknowledging P.seqno
		 *  Drop packet and return
		 */
		if (dp->dccps_role != DCCP_ROLE_LISTEN)
			goto send_sync;
		goto check_seq;
	case DCCP_PKT_RESPONSE:
		if (dp->dccps_role != DCCP_ROLE_CLIENT)
			goto send_sync;
check_seq:
		if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
send_sync:
			dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		}
		break;
	}

	DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
discard:
	__kfree_skb(skb);
	return 0;
}

static int dccp_rcv_request_sent_state_process(struct sock *sk,
					       struct sk_buff *skb,
					       const struct dccp_hdr *dh,
					       const unsigned len)
{
	/* 
	 *  Step 4: Prepare sequence numbers in REQUEST
	 *     If S.state == REQUEST,
	 *	  If (P.type == Response or P.type == Reset)
	 *		and S.AWL <= P.ackno <= S.AWH,
	 *	     / * Set sequence number variables corresponding to the
	 *		other endpoint, so P will pass the tests in Step 6 * /
	 *	     Set S.GSR, S.ISR, S.SWL, S.SWH
	 *	     / * Response processing continues in Step 10; Reset
	 *		processing continues in Step 9 * /
	*/
	if (dh->dccph_type == DCCP_PKT_RESPONSE) {
		const struct inet_connection_sock *icsk = inet_csk(sk);
		struct dccp_sock *dp = dccp_sk(sk);

		/* Stop the REQUEST timer */
		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
		BUG_TRAP(sk->sk_send_head != NULL);
		__kfree_skb(sk->sk_send_head);
		sk->sk_send_head = NULL;

		if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
			       dp->dccps_awl, dp->dccps_awh)) {
			dccp_pr_debug("invalid ackno: S.AWL=%llu, "
				      "P.ackno=%llu, S.AWH=%llu \n",
				      (unsigned long long)dp->dccps_awl,
			   (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
				      (unsigned long long)dp->dccps_awh);
			goto out_invalid_packet;
		}

		dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);

		if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
		    ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
			ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
			ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
			/* FIXME: send appropriate RESET code */
			goto out_invalid_packet;
		}

		dccp_sync_mss(sk, dp->dccps_pmtu_cookie);

		/*
		 *    Step 10: Process REQUEST state (second part)
		 *       If S.state == REQUEST,
		 *	  / * If we get here, P is a valid Response from the
		 *	      server (see Step 4), and we should move to
		 *	      PARTOPEN state. PARTOPEN means send an Ack,
		 *	      don't send Data packets, retransmit Acks
		 *	      periodically, and always include any Init Cookie
		 *	      from the Response * /
		 *	  S.state := PARTOPEN
		 *	  Set PARTOPEN timer
		 * 	  Continue with S.state == PARTOPEN
		 *	  / * Step 12 will send the Ack completing the
		 *	      three-way handshake * /
		 */
		dccp_set_state(sk, DCCP_PARTOPEN);

		/* Make sure socket is routed, for correct metrics. */
		inet_sk_rebuild_header(sk);

		if (!sock_flag(sk, SOCK_DEAD)) {
			sk->sk_state_change(sk);
			sk_wake_async(sk, 0, POLL_OUT);
		}

		if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
		    icsk->icsk_accept_queue.rskq_defer_accept) {
			/* Save one ACK. Data will be ready after
			 * several ticks, if write_pending is set.
			 *
			 * It may be deleted, but with this feature tcpdumps
			 * look so _wonderfully_ clever, that I was not able
			 * to stand against the temptation 8)     --ANK
			 */
			/*
			 * OK, in DCCP we can as well do a similar trick, its
			 * even in the draft, but there is no need for us to
			 * schedule an ack here, as dccp_sendmsg does this for
			 * us, also stated in the draft. -acme
			 */
			__kfree_skb(skb);
			return 0;
		} 
		dccp_send_ack(sk);
		return -1;
	}

out_invalid_packet:
	return 1; /* dccp_v4_do_rcv will send a reset, but...
		     FIXME: the reset code should be
			    DCCP_RESET_CODE_PACKET_ERROR */
}

static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
						   struct sk_buff *skb,
						   const struct dccp_hdr *dh,
						   const unsigned len)
{
	int queued = 0;

	switch (dh->dccph_type) {
	case DCCP_PKT_RESET:
		inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
		break;
	case DCCP_PKT_DATAACK:
	case DCCP_PKT_ACK:
		/*
		 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
		 * here but only if we haven't used the DELACK timer for
		 * something else, like sending a delayed ack for a TIMESTAMP
		 * echo, etc, for now were not clearing it, sending an extra
		 * ACK when there is nothing else to do in DELACK is not a big
		 * deal after all.
		 */

		/* Stop the PARTOPEN timer */
		if (sk->sk_state == DCCP_PARTOPEN)
			inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);

		dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
		dccp_set_state(sk, DCCP_OPEN);

		if (dh->dccph_type == DCCP_PKT_DATAACK) {
			dccp_rcv_established(sk, skb, dh, len);
			queued = 1; /* packet was queued
				       (by dccp_rcv_established) */
		}
		break;
	}

	return queued;
}

int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
			   struct dccp_hdr *dh, unsigned len)
{
	struct dccp_sock *dp = dccp_sk(sk);
	const int old_state = sk->sk_state;
	int queued = 0;

	if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING) {
		if (dccp_check_seqno(sk, skb))
			goto discard;

		/*
		 * Step 8: Process options and mark acknowledgeable
		 */
		if (dccp_parse_options(sk, skb))
			goto discard;

		if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
		    DCCP_PKT_WITHOUT_ACK_SEQ)
			dccp_event_ack_recv(sk, skb);

		ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
		ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);

		/*
		 * FIXME: check ECN to see if we should use
		 * DCCP_ACKPKTS_STATE_ECN_MARKED
		 */
		if (dp->dccps_options.dccpo_send_ack_vector) {
			if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
					     DCCP_SKB_CB(skb)->dccpd_seq,
					     DCCP_ACKPKTS_STATE_RECEIVED))
				goto discard;
			/*
			 * FIXME: this activation is probably wrong, have to
			 * study more TCP delack machinery and how it fits into
			 * DCCP draft, but for now it kinda "works" 8)
			 */
			if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
			     DCCP_MAX_SEQNO + 1) &&
			    !inet_csk_ack_scheduled(sk)) {
				inet_csk_schedule_ack(sk);
				inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
							  TCP_DELACK_MIN,
							  DCCP_RTO_MAX);
			}
		}
	}

	/*
	 *  Step 9: Process Reset
	 *	If P.type == Reset,
	 *		Tear down connection
	 *		S.state := TIMEWAIT
	 *		Set TIMEWAIT timer
	 *		Drop packet and return
	*/
	if (dh->dccph_type == DCCP_PKT_RESET) {
		/*
		 * Queue the equivalent of TCP fin so that dccp_recvmsg
		 * exits the loop
		 */
		dccp_fin(sk, skb);
		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
		return 0;
		/*
		 *   Step 7: Check for unexpected packet types
		 *      If (S.is_server and P.type == CloseReq)
		 *	    or (S.is_server and P.type == Response)
		 *	    or (S.is_client and P.type == Request)
		 *	    or (S.state == RESPOND and P.type == Data),
		 *	  Send Sync packet acknowledging P.seqno
		 *	  Drop packet and return
		 */
	} else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
		    (dh->dccph_type == DCCP_PKT_RESPONSE ||
		     dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
		    (dp->dccps_role == DCCP_ROLE_CLIENT &&
		     dh->dccph_type == DCCP_PKT_REQUEST) ||
		    (sk->sk_state == DCCP_RESPOND &&
		     dh->dccph_type == DCCP_PKT_DATA)) {
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		goto discard;
	}

	switch (sk->sk_state) {
	case DCCP_CLOSED:
		return 1;

	case DCCP_LISTEN:
		if (dh->dccph_type == DCCP_PKT_ACK ||
		    dh->dccph_type == DCCP_PKT_DATAACK)
			return 1;

		if (dh->dccph_type == DCCP_PKT_RESET)
			goto discard;

		if (dh->dccph_type == DCCP_PKT_REQUEST) {
			if (dccp_v4_conn_request(sk, skb) < 0)
				return 1;

			/* FIXME: do congestion control initialization */
			goto discard;
		}
		goto discard;

	case DCCP_REQUESTING:
		/* FIXME: do congestion control initialization */

		queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
		if (queued >= 0)
			return queued;

		__kfree_skb(skb);
		return 0;

	case DCCP_RESPOND:
	case DCCP_PARTOPEN:
		queued = dccp_rcv_respond_partopen_state_process(sk, skb,
								 dh, len);
		break;
	}

	if (dh->dccph_type == DCCP_PKT_ACK ||
	    dh->dccph_type == DCCP_PKT_DATAACK) {
		switch (old_state) {
		case DCCP_PARTOPEN:
			sk->sk_state_change(sk);
			sk_wake_async(sk, 0, POLL_OUT);
			break;
		}
	}

	if (!queued) { 
discard:
		__kfree_skb(skb);
	}
	return 0;
}
Commit	Line	Data
7c657876 ACM	1	/*
	2	* net/dccp/input.c
	3	*
	4	* An implementation of the DCCP protocol
	5	* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version
	10	* 2 of the License, or (at your option) any later version.
	11	*/
	12
	13	#include <linux/config.h>
	14	#include <linux/dccp.h>
	15	#include <linux/skbuff.h>
	16
	17	#include <net/sock.h>
	18
	19	#include "ccid.h"
	20	#include "dccp.h"
	21
	22	static void dccp_fin(struct sock sk, struct sk_buff skb)
	23	{
	24	sk->sk_shutdown \|= RCV_SHUTDOWN;
	25	sock_set_flag(sk, SOCK_DONE);
	26	__skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
	27	__skb_queue_tail(&sk->sk_receive_queue, skb);
	28	skb_set_owner_r(skb, sk);
	29	sk->sk_data_ready(sk, 0);
	30	}
	31
	32	static void dccp_rcv_close(struct sock sk, struct sk_buff skb)
	33	{
	34	switch (sk->sk_state) {
	35	case DCCP_PARTOPEN:
	36	case DCCP_OPEN:
	37	dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
	38	dccp_fin(sk, skb);
	39	dccp_set_state(sk, DCCP_CLOSED);
	40	break;
	41	}
	42	}
	43
	44	static void dccp_rcv_closereq(struct sock sk, struct sk_buff skb)
	45	{
	46	/*
	47	* Step 7: Check for unexpected packet types
	48	* If (S.is_server and P.type == CloseReq)
	49	* Send Sync packet acknowledging P.seqno
	50	* Drop packet and return
	51	*/
	52	if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
	53	dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	54	return;
	55	}
	56
	57	switch (sk->sk_state) {
	58	case DCCP_PARTOPEN:
	59	case DCCP_OPEN:
	60	dccp_set_state(sk, DCCP_CLOSING);
	61	dccp_send_close(sk);
	62	break;
	63	}
	64	}
65
66	static inline void dccp_event_ack_recv(struct sock sk, struct sk_buff skb)
67	{
68	struct dccp_sock *dp = dccp_sk(sk);
69
70	if (dp->dccps_options.dccpo_send_ack_vector)
71	dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
72	DCCP_SKB_CB(skb)->dccpd_ack_seq);
73	}
74
75	static int dccp_check_seqno(struct sock sk, struct sk_buff skb)
76	{
77	const struct dccp_hdr *dh = dccp_hdr(skb);
78	struct dccp_sock *dp = dccp_sk(sk);
79	u64 lswl = dp->dccps_swl;
80	u64 lawl = dp->dccps_awl;
81
82	/*
83	* Step 5: Prepare sequence numbers for Sync
84	* If P.type == Sync or P.type == SyncAck,
85	* If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
86	* / * P is valid, so update sequence number variables
87	* accordingly. After this update, P will pass the tests
88	* in Step 6. A SyncAck is generated if necessary in
89	* Step 15 * /
90	* Update S.GSR, S.SWL, S.SWH
91	* Otherwise,
92	* Drop packet and return
93	*/
94	if (dh->dccph_type == DCCP_PKT_SYNC \|\|
95	dh->dccph_type == DCCP_PKT_SYNCACK) {
7690af3f ACM	96	if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
7690af3f ACM	97	dp->dccps_awl, dp->dccps_awh) &&
7c657876 ACM	98	!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
	99	dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	100	else
	101	return -1;
	102	/*
	103	* Step 6: Check sequence numbers
	104	* Let LSWL = S.SWL and LAWL = S.AWL
	105	* If P.type == CloseReq or P.type == Close or P.type == Reset,
	106	* LSWL := S.GSR + 1, LAWL := S.GAR
	107	* If LSWL <= P.seqno <= S.SWH
	108	* and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
	109	* Update S.GSR, S.SWL, S.SWH
	110	* If P.type != Sync,
	111	* Update S.GAR
	112	* Otherwise,
	113	* Send Sync packet acknowledging P.seqno
	114	* Drop packet and return
	115	*/
	116	} else if (dh->dccph_type == DCCP_PKT_CLOSEREQ \|\|
	117	dh->dccph_type == DCCP_PKT_CLOSE \|\|
	118	dh->dccph_type == DCCP_PKT_RESET) {
	119	lswl = dp->dccps_gsr;
	120	dccp_inc_seqno(&lswl);
	121	lawl = dp->dccps_gar;
	122	}
	123
	124	if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
	125	(DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ \|\|
7690af3f ACM	126	between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
7690af3f ACM	127	lawl, dp->dccps_awh))) {
7c657876 ACM	128	dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	129
	130	if (dh->dccph_type != DCCP_PKT_SYNC &&
7690af3f ACM	131	(DCCP_SKB_CB(skb)->dccpd_ack_seq !=
7690af3f ACM	132	DCCP_PKT_WITHOUT_ACK_SEQ))
7c657876 ACM	133	dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
	134	} else {
	135	dccp_pr_debug("Step 6 failed, sending SYNC...\n");
	136	dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	137	return -1;
	138	}
	139
	140	return 0;
	141	}
	142
	143	int dccp_rcv_established(struct sock sk, struct sk_buff skb,
	144	const struct dccp_hdr *dh, const unsigned len)
	145	{
	146	struct dccp_sock *dp = dccp_sk(sk);
	147
	148	if (dccp_check_seqno(sk, skb))
	149	goto discard;
	150
	151	if (dccp_parse_options(sk, skb))
	152	goto discard;
	153
	154	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
	155	dccp_event_ack_recv(sk, skb);
	156
	157	/*
	158	* FIXME: check ECN to see if we should use
	159	* DCCP_ACKPKTS_STATE_ECN_MARKED
	160	*/
	161	if (dp->dccps_options.dccpo_send_ack_vector) {
	162	struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
	163
	164	if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
	165	DCCP_SKB_CB(skb)->dccpd_seq,
	166	DCCP_ACKPKTS_STATE_RECEIVED)) {
7690af3f ACM	167	LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable "
7690af3f ACM	168	"packets buffer full!\n");
7c657876 ACM	169	ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
7c657876 ACM	170	inet_csk_schedule_ack(sk);
7690af3f ACM	171	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	172	TCP_DELACK_MIN,
	173	DCCP_RTO_MAX);
7c657876 ACM	174	goto discard;
	175	}
	176
	177	/*
	178	* FIXME: this activation is probably wrong, have to study more
	179	* TCP delack machinery and how it fits into DCCP draft, but
	180	* for now it kinda "works" 8)
	181	*/
	182	if (!inet_csk_ack_scheduled(sk)) {
	183	inet_csk_schedule_ack(sk);
7690af3f ACM	184	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
7690af3f ACM	185	DCCP_RTO_MAX);
7c657876 ACM	186	}
	187	}
	188
	189	ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
	190	ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
	191
	192	switch (dccp_hdr(skb)->dccph_type) {
	193	case DCCP_PKT_DATAACK:
	194	case DCCP_PKT_DATA:
	195	/*
7690af3f ACM	196	* FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
7690af3f ACM	197	* option if it is.
7c657876 ACM	198	*/
	199	__skb_pull(skb, dh->dccph_doff * 4);
	200	__skb_queue_tail(&sk->sk_receive_queue, skb);
	201	skb_set_owner_r(skb, sk);
	202	sk->sk_data_ready(sk, 0);
	203	return 0;
	204	case DCCP_PKT_ACK:
	205	goto discard;
	206	case DCCP_PKT_RESET:
	207	/*
	208	* Step 9: Process Reset
	209	* If P.type == Reset,
	210	* Tear down connection
	211	* S.state := TIMEWAIT
	212	* Set TIMEWAIT timer
	213	* Drop packet and return
	214	*/
	215	dccp_fin(sk, skb);
	216	dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
	217	return 0;
	218	case DCCP_PKT_CLOSEREQ:
	219	dccp_rcv_closereq(sk, skb);
	220	goto discard;
	221	case DCCP_PKT_CLOSE:
	222	dccp_rcv_close(sk, skb);
	223	return 0;
	224	case DCCP_PKT_REQUEST:
	225	/* Step 7
	226	* or (S.is_server and P.type == Response)
	227	* or (S.is_client and P.type == Request)
	228	* or (S.state >= OPEN and P.type == Request
	229	* and P.seqno >= S.OSR)
	230	* or (S.state >= OPEN and P.type == Response
	231	* and P.seqno >= S.OSR)
	232	* or (S.state == RESPOND and P.type == Data),
	233	* Send Sync packet acknowledging P.seqno
	234	* Drop packet and return
	235	*/
	236	if (dp->dccps_role != DCCP_ROLE_LISTEN)
	237	goto send_sync;
	238	goto check_seq;
	239	case DCCP_PKT_RESPONSE:
	240	if (dp->dccps_role != DCCP_ROLE_CLIENT)
	241	goto send_sync;
	242	check_seq:
	243	if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
	244	send_sync:
	245	dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	246	}
	247	break;
	248	}
	249
	250	DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
	251	discard:
	252	__kfree_skb(skb);
	253	return 0;
	254	}
	255
	256	static int dccp_rcv_request_sent_state_process(struct sock *sk,
	257	struct sk_buff *skb,
	258	const struct dccp_hdr *dh,
	259	const unsigned len)
	260	{
	261	/*
262	* Step 4: Prepare sequence numbers in REQUEST
263	* If S.state == REQUEST,
264	* If (P.type == Response or P.type == Reset)
265	* and S.AWL <= P.ackno <= S.AWH,
266	* / * Set sequence number variables corresponding to the
267	* other endpoint, so P will pass the tests in Step 6 * /
268	* Set S.GSR, S.ISR, S.SWL, S.SWH
269	* / * Response processing continues in Step 10; Reset
270	* processing continues in Step 9 * /
271	*/
272	if (dh->dccph_type == DCCP_PKT_RESPONSE) {
273	const struct inet_connection_sock *icsk = inet_csk(sk);
274	struct dccp_sock *dp = dccp_sk(sk);
275
276	/* Stop the REQUEST timer */
277	inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
278	BUG_TRAP(sk->sk_send_head != NULL);
279	__kfree_skb(sk->sk_send_head);
280	sk->sk_send_head = NULL;
281
7690af3f ACM	282	if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
	283	dp->dccps_awl, dp->dccps_awh)) {
	284	dccp_pr_debug("invalid ackno: S.AWL=%llu, "
	285	"P.ackno=%llu, S.AWH=%llu \n",
	286	(unsigned long long)dp->dccps_awl,
	287	(unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
	288	(unsigned long long)dp->dccps_awh);
7c657876 ACM	289	goto out_invalid_packet;
	290	}
	291
	292	dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
	293	dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	294
	295	if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 \|\|
	296	ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
	297	ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
	298	ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
	299	/* FIXME: send appropriate RESET code */
	300	goto out_invalid_packet;
	301	}
	302
	303	dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
	304
	305	/*
	306	* Step 10: Process REQUEST state (second part)
	307	* If S.state == REQUEST,
7690af3f ACM	308	* / * If we get here, P is a valid Response from the
	309	* server (see Step 4), and we should move to
	310	* PARTOPEN state. PARTOPEN means send an Ack,
	311	* don't send Data packets, retransmit Acks
	312	* periodically, and always include any Init Cookie
	313	* from the Response * /
7c657876 ACM	314	* S.state := PARTOPEN
	315	* Set PARTOPEN timer
	316	* Continue with S.state == PARTOPEN
7690af3f ACM	317	* / * Step 12 will send the Ack completing the
7690af3f ACM	318	* three-way handshake * /
7c657876 ACM	319	*/
	320	dccp_set_state(sk, DCCP_PARTOPEN);
	321
	322	/* Make sure socket is routed, for correct metrics. */
	323	inet_sk_rebuild_header(sk);
	324
	325	if (!sock_flag(sk, SOCK_DEAD)) {
	326	sk->sk_state_change(sk);
	327	sk_wake_async(sk, 0, POLL_OUT);
	328	}
	329
	330	if (sk->sk_write_pending \|\| icsk->icsk_ack.pingpong \|\|
	331	icsk->icsk_accept_queue.rskq_defer_accept) {
	332	/* Save one ACK. Data will be ready after
	333	* several ticks, if write_pending is set.
	334	*
	335	* It may be deleted, but with this feature tcpdumps
	336	* look so _wonderfully_ clever, that I was not able
	337	* to stand against the temptation 8) --ANK
	338	*/
	339	/*
	340	* OK, in DCCP we can as well do a similar trick, its
	341	* even in the draft, but there is no need for us to
	342	* schedule an ack here, as dccp_sendmsg does this for
	343	* us, also stated in the draft. -acme
	344	*/
	345	__kfree_skb(skb);
	346	return 0;
	347	}
	348	dccp_send_ack(sk);
	349	return -1;
	350	}
	351
	352	out_invalid_packet:
	353	return 1; /* dccp_v4_do_rcv will send a reset, but...
7690af3f ACM	354	FIXME: the reset code should be
7690af3f ACM	355	DCCP_RESET_CODE_PACKET_ERROR */
7c657876 ACM	356	}
	357
	358	static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
	359	struct sk_buff *skb,
	360	const struct dccp_hdr *dh,
	361	const unsigned len)
	362	{
	363	int queued = 0;
	364
	365	switch (dh->dccph_type) {
	366	case DCCP_PKT_RESET:
	367	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
	368	break;
	369	case DCCP_PKT_DATAACK:
	370	case DCCP_PKT_ACK:
	371	/*
7690af3f ACM	372	* FIXME: we should be reseting the PARTOPEN (DELACK) timer
	373	* here but only if we haven't used the DELACK timer for
	374	* something else, like sending a delayed ack for a TIMESTAMP
	375	* echo, etc, for now were not clearing it, sending an extra
	376	* ACK when there is nothing else to do in DELACK is not a big
	377	* deal after all.
7c657876 ACM	378	*/
	379
	380	/* Stop the PARTOPEN timer */
	381	if (sk->sk_state == DCCP_PARTOPEN)
	382	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
	383
	384	dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
	385	dccp_set_state(sk, DCCP_OPEN);
	386
	387	if (dh->dccph_type == DCCP_PKT_DATAACK) {
	388	dccp_rcv_established(sk, skb, dh, len);
7690af3f ACM	389	queued = 1; /* packet was queued
7690af3f ACM	390	(by dccp_rcv_established) */
7c657876 ACM	391	}
	392	break;
	393	}
	394
	395	return queued;
	396	}
	397
	398	int dccp_rcv_state_process(struct sock sk, struct sk_buff skb,
	399	struct dccp_hdr *dh, unsigned len)
	400	{
	401	struct dccp_sock *dp = dccp_sk(sk);
	402	const int old_state = sk->sk_state;
	403	int queued = 0;
	404
	405	if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING) {
	406	if (dccp_check_seqno(sk, skb))
	407	goto discard;
	408
	409	/*
	410	* Step 8: Process options and mark acknowledgeable
	411	*/
	412	if (dccp_parse_options(sk, skb))
	413	goto discard;
	414
7690af3f ACM	415	if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
7690af3f ACM	416	DCCP_PKT_WITHOUT_ACK_SEQ)
7c657876 ACM	417	dccp_event_ack_recv(sk, skb);
	418
	419	ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
	420	ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
	421
	422	/*
	423	* FIXME: check ECN to see if we should use
	424	* DCCP_ACKPKTS_STATE_ECN_MARKED
	425	*/
	426	if (dp->dccps_options.dccpo_send_ack_vector) {
	427	if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
	428	DCCP_SKB_CB(skb)->dccpd_seq,
	429	DCCP_ACKPKTS_STATE_RECEIVED))
	430	goto discard;
	431	/*
7690af3f ACM	432	* FIXME: this activation is probably wrong, have to
	433	* study more TCP delack machinery and how it fits into
	434	* DCCP draft, but for now it kinda "works" 8)
7c657876	435	*/
7690af3f ACM	436	if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
7690af3f ACM	437	DCCP_MAX_SEQNO + 1) &&
7c657876 ACM	438	!inet_csk_ack_scheduled(sk)) {
7c657876 ACM	439	inet_csk_schedule_ack(sk);
7690af3f ACM	440	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	441	TCP_DELACK_MIN,
	442	DCCP_RTO_MAX);
7c657876 ACM	443	}
	444	}
	445	}
	446
	447	/*
	448	* Step 9: Process Reset
	449	* If P.type == Reset,
	450	* Tear down connection
	451	* S.state := TIMEWAIT
	452	* Set TIMEWAIT timer
	453	* Drop packet and return
	454	*/
	455	if (dh->dccph_type == DCCP_PKT_RESET) {
7690af3f ACM	456	/*
	457	* Queue the equivalent of TCP fin so that dccp_recvmsg
	458	* exits the loop
	459	*/
7c657876 ACM	460	dccp_fin(sk, skb);
	461	dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
	462	return 0;
	463	/*
	464	* Step 7: Check for unexpected packet types
	465	* If (S.is_server and P.type == CloseReq)
	466	* or (S.is_server and P.type == Response)
	467	* or (S.is_client and P.type == Request)
	468	* or (S.state == RESPOND and P.type == Data),
	469	* Send Sync packet acknowledging P.seqno
	470	* Drop packet and return
	471	*/
	472	} else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
7690af3f ACM	473	(dh->dccph_type == DCCP_PKT_RESPONSE \|\|
7690af3f ACM	474	dh->dccph_type == DCCP_PKT_CLOSEREQ)) \|\|
7c657876 ACM	475	(dp->dccps_role == DCCP_ROLE_CLIENT &&
7c657876 ACM	476	dh->dccph_type == DCCP_PKT_REQUEST) \|\|
7690af3f ACM	477	(sk->sk_state == DCCP_RESPOND &&
7690af3f ACM	478	dh->dccph_type == DCCP_PKT_DATA)) {
7c657876 ACM	479	dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
	480	goto discard;
	481	}
	482
	483	switch (sk->sk_state) {
	484	case DCCP_CLOSED:
	485	return 1;
	486
	487	case DCCP_LISTEN:
	488	if (dh->dccph_type == DCCP_PKT_ACK \|\|
	489	dh->dccph_type == DCCP_PKT_DATAACK)
	490	return 1;
	491
	492	if (dh->dccph_type == DCCP_PKT_RESET)
	493	goto discard;
	494
	495	if (dh->dccph_type == DCCP_PKT_REQUEST) {
	496	if (dccp_v4_conn_request(sk, skb) < 0)
	497	return 1;
	498
	499	/* FIXME: do congestion control initialization */
	500	goto discard;
	501	}
	502	goto discard;
	503
	504	case DCCP_REQUESTING:
	505	/* FIXME: do congestion control initialization */
	506
	507	queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
	508	if (queued >= 0)
	509	return queued;
	510
	511	__kfree_skb(skb);
	512	return 0;
	513
	514	case DCCP_RESPOND:
	515	case DCCP_PARTOPEN:
7690af3f ACM	516	queued = dccp_rcv_respond_partopen_state_process(sk, skb,
7690af3f ACM	517	dh, len);
7c657876 ACM	518	break;
	519	}
	520
7690af3f ACM	521	if (dh->dccph_type == DCCP_PKT_ACK \|\|
7690af3f ACM	522	dh->dccph_type == DCCP_PKT_DATAACK) {
7c657876 ACM	523	switch (old_state) {
	524	case DCCP_PARTOPEN:
	525	sk->sk_state_change(sk);
	526	sk_wake_async(sk, 0, POLL_OUT);
	527	break;
	528	}
	529	}
	530
	531	if (!queued) {
	532	discard:
	533	__kfree_skb(skb);
	534	}
	535	return 0;
	536	}